Wheatstone bridge & strain gauges worksheet with answers

Free printable Wheatstone bridge & strain gauges worksheet: 6 problems from easy to exam level, with an answer key. Print it or save it as a PDF.

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1.Easy

The bridge shown is supplied with V_s = 12 V and its output is open. Find the current I_s drawn from the supply, in mA.

V_s = 12 VR₁ = 80 ΩR₂ = 10 ΩR₃ = 500 ΩR₄ = 400 Ω

I_s = mA

2.Easy

In the bridge shown, V_s = 15 V, R₁ = 500 Ω and R₂ = 500 Ω. Find the voltage V_a of node a with respect to the negative supply rail.

V_s = 15 VR₁ = 500 ΩR₂ = 500 ΩR₃ = 800 ΩR₄ = 300 Ω

V_a = V

3.Medium

A bridge with four 250 Ω arms is supplied with 3 V. When the sensor R₂ changes, the output reads V_ab = 29.41 mV. Find the exact change ΔR of R₂.

V_s = 3 VR = 250 ΩV_ab = 29.41 mV

ΔR = Ω

4.Medium

A bridge has four 400 Ω arms and V_s = 12 V. The sensor R₂ increases by ΔR = 40 Ω. Find the exact output V_ab in mV.

V_s = 12 VR = 400 ΩΔR = 40 Ω

V_ab = mV

5.Hard

A bridge with 1000 Ω arms is excited with 2.5 V and has one active gauge (quarter bridge). The gauge factor is 2 and the strain is 600 µε. Find the bridge output V_o in mV.

V_s = 2.5 VGF = 2ε = 600 µε

V_o = mV

6.Hard

A bridge with 350 Ω arms is excited with 3 V and has two active gauges in adjacent arms, one in tension and one in compression (half bridge). The gauge factor is 2.05 and the strain is 1500 µε. Find the bridge output V_o in mV.

V_s = 3 VGF = 2.05ε = 1500 µε

V_o = mV

Answer key

1. I_s = 146.7 mA
2. V_a = 7.5 V
3. ΔR = 9.999 Ω
4. V_ab = 285.7 mV
5. V_o = 0.75 mV
6. V_o = 4.612 mV

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